Visual C++ error

Does anyone know how to fix this error? All I have is a header file and a source file for a class.

1>MSVCRTD.lib(exe_main.obj) : error LNK2019: unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

#ifndef POINT_H
#define POINT_H

#include 

class Point {
public:
    Point();
    Point(unsigned int x, unsigned int y);
    bool operator== (const Point &other) const;


    unsigned int m_x;
    unsigned int m_y;

    friend std::ostream& operator<<(std::ostream &sout, const Point &pt);
};

#endif

AND

#include "Point.h"


Point::Point() {}  // Needed because of existence of other constructors

Point::Point(unsigned int x, unsigned int y) {
    m_x = x;
    m_y = y;

}

// Note: automatically get copy constructor

bool
Point::operator== (const Point &other) const {
    return (m_x == other.m_x && m_y == other.m_y);
}

std::ostream& operator<<(std::ostream &sout, const Point &pt) {

    sout << "(" << pt.m_x << ", " << pt.m_y << ")";
    return sout;
}